1. Technical Field
The present invention generally relates to an improved method for manufacturing sliders for magnetic recording heads, and in particular to the ion milling of the trailing edge of the slider. Still more particularly, the present invention relates to the use of ion milling over the entire slider or with the slider masked except for the trailing edge in order to change the topography of the trailing edge.
2. Description of the Related Art
Digital magnetic recording devices for data storage generally comprise a thin film magnetic recording disk and a head which is moved above the surface of the rotating disk to electromagnetically read and write information on the disk. Advanced thin film magnetic recording disks generally comprise a rigid substrate, a magnetic layer such as a cobalt-based metal alloy, a protective amorphous carbon layer and a lubricant layer, such as perfluoropolyether disposed on the carbon overcoat.
During operation of the disk drive system, an actuator mechanism moves the magnetic transducer to a desired radial position on the surface of the rotating disk where the head electromagnetically reads or writes data. Usually, the head is integrally mounted in a carrier or support referred to as a xe2x80x9csliderxe2x80x9d. The slider is generally rectangular in shape and consists of two portions: a substrate portion and a head portion formed on an end face of the slider portion. Typically, this end face of the slider will constitute the slider trailing edge when the slider is suspended adjacent to a rotating recording disk.
The substrate portion of the slider can be made from ceramic material such as Al2O3xe2x80x94TiC, silicon carbide, zirconium oxide, or other suitable material. The head portion of the slider is typically a thin layer of alumina (Al2O3), or alumina overcoat, formed on the trailing edge face of the slider in which the magnetic portion of the head is embedded. The slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to glide over moving air in order to maintain a uniform distance from the surface of the rotating disk, thereby preventing the head from undesirable contacting the disk.
Typically, a slider is formed with an aerodynamic pattern of protrusions (air bearing design) on its air bearing surface (xe2x80x9cABSxe2x80x9d), or substrate surface, which enables the slider to fly at a constant height close to the disk during operation of the disk drive. The recording density of the magnetic disk drive system is dependent upon the distance between a transducer and the magnetic media. One goal of the air bearing slider design is to xe2x80x9cflyxe2x80x9d a slider as closely as possible to a magnetic medium while avoiding physical impact with the medium. Smaller spacings, or xe2x80x9cfly heightsxe2x80x9d, are desired so that the transducer can distinguish between the varying magnetic fields emanating from closely spaced regions on the disk.
However, the benefit of closer spacing is contrasted by the adverse effect on the mechanical reliability of the slider. As the distance between the slider and the disk decreases, as it does with every generation of storage device, the probability of contact between the two surfaces increases, thus causing wear on both contacting surfaces that could ultimately lead to loss of data. The probability of contact between the slider and disk increases when any part of the trailing edge protrudes above the air bearing surface of the slider. Further, the amount of exposure that certain transducer parts such as the read head face can influence its performance. Ideally, the read head should be flush with the alumina material making up the slider surface. Thus, the precise topography surrounding the transducers is vital to the performance of the slider read/write head.
In the manufacturing of the sliders, the lapping process determines the final trailing edge topography of the slider. However, the desired profile may be different from what results from the lapping process. More particularly, it is often desirable to change the heights of the magnetic recording heads relative to the substrate. Making the recording heads lower in height relative to the substrate surface of the slider would be ideal, protecting the heads from physical contact with the disks moving below (or above) them. Thus, it would be beneficial to tailor the trailing edge profile to any defined shape. The present invention is directed towards such means of tailoring a trailing edge profile through the use of ion milling.
It is therefore one object of the present invention to provide a method of altering the topography of the trailing edge of a slider.
It is another object of the present invention to provide a method of decreasing the likelihood of physical contact between a moving disk and the magnetic recording heads of the slider.
It is yet another object of the present invention to improve the thermal asperity characteristics of the magnetic recording heads of a slider.
It is yet another object of the present invention to provide for a two-step process of altering the topography of the slider trailing edge in a first step, and then removing a thin layer of material to clean the trailing edge surface, thus allowing a carbon coating to better adhere to the trailing edge.
The foregoing objects are achieved as is now described, wherein ion milling is used to alter the topography of a trailing edge of a slider, the slider having a substrate surface, at least one magnetic recording head imbedded in an alumina undercoat, and a vertical axis relative to the substrate surface. The steps include first applying an alumina overcoat to at least the trailing edge, followed by lapping at least the trailing edge of the slider. The slider (or sliders) is then placed on a pallet that rotates, exposing the trailing edge to an ion beam. The ion beam is generated using an etchant gas such as Argon, or a mixture of gases such as Argon and Hydrogen, or Argon and CHF3. The trailing edge (or trailing edges) are then exposed at least once to the ion beam at a predetermined milling angle and predetermined time, the milling angle being the angle made by the ion beam relative to the vertical axis of the slider. The milling angle is typically between about 0xc2x0 and 85xc2x0, and 0xc2x0 and xe2x88x9285xc2x0 (hereinafter, reference to a range of angles always inherently includes the negative range, unless otherwise stated. Thus, reference to a range of xe2x80x9c0xc2x0 and 50xc2x0xe2x80x9d means xe2x88x9250xc2x0 and +50xc2x0, and reference to the range xe2x80x9c70xc2x0 to 85xc2x0xe2x80x9d means xe2x88x9270xc2x0 to xe2x88x9285xc2x0 and +70xc2x0 to +85xc2x0).
If it is necessary to lower the levels of the magnetic recording head material to produce the desired topography on the trailing edge, a milling angle of between 0xc2x0 and 50xc2x0 is chosen, wherein the magnetic recording head material is typically etched away to a greater extent than the alumina undercoat and alumina overcoat. If changes in the topography of the alumina undercoat and/or alumina overcoat are desired such as to clean the surface in preparation for a subsequent carbon or polymer coating, a milling angle of between 70xc2x0 and 85xc2x0 is chosen. The larger milling angles will tend to differentially mill away the alumina material to a greater extent than the head material.
Various parameters can be manipulated to alter the ion milling properties of the method. The milling angle, time of exposure, and power level of the ion generating source and identity of the etchant gas can all be individually manipulated or manipulated together.
The above as well as additional objectives, features, and advantages of the present invention will become apparent in the following detailed written description.